Constructing interconnected spherical hollow conductive networks in silver platelets/reduced graphene oxide foam/epoxy nanocomposites for superior electromagnetic interference shielding effectiveness
How to significantly increase the electromagnetic interference (EMI) shielding performances by improving the electrical conductivities is still a serious challenge. Herein, we have explored and prepared a 3D silver platelets/reduced graphene oxide foam (AgPs/rGF) with numerous regular spherical hollow structures, which ingeniously achieved uniform dispersion of the AgPs along 3D rGO network via sol-gel template method. Combining AgPs/rGF with epoxy resin (EP), the 3D AgPs/rGF/EP nanocomposites with highly regular segregated structures were successfully fabricated. Due to interconnected spherical hollow conductive networks of the AgPs/rGF and the interfacial synergy between AgPs/rGF and EP, the 3D AgPs/rGF/EP nanocomposites containing 0.44 vol% rGF and 0.94 vol% AgPs show the maximum EMI shielding effectiveness (SE) value of 58 dB at X-band (shielding 99.9998% of incident electromagnetic waves), 274% improvement in comparison to that of 3D rGF/EP nanocomposites (～21 dB). The corresponding electrical conductivity improves from 0.1 to 45.3 S/m, dielectric loss increases from ～0.6 to ～0.8. In addition, the theoretical minimum skin depth of the 3D AgPs/rGF/EP nanocomposites is calculated by analyzing skin effect. It provides a guideline for fabricating lightweight, thin and multi-functional shielding nanocomposites in the key fields of spacecraft and high precision electronics.